Amorphous Solids and Crystalline Solids - Definition,Explanation,Difference Between Crystalline And Amorphous Solids

 

Introduction Of Crystalline Solid And Amorphous Solid

Solids can be classified as crystalline or amorphous based on the nature of the order(means where everything is in its right place) in the arrangement or pattern of their constituents (one of the parts that form something) particles. 

Crystalline Solid

A Crystalline solid usually consists of (or is made up of )a large number of small crystals, each of them having a definite characteristic geometrical shape known as Crystalline Solid. 

[Geometrical Shape

Geometric shapes are mathematical shapes. They are perfect (in shape) and regular. 

They are characterized by a straight line, angle, and point but a perfect circle is it has no straight line or point this is an exception.

Examples of Geometrical Shapes are square, rectangle, triangle, parallelogram, hexagons, etc. ]

Or 

Solid in which particles have a regular (pattern) arrangement known as Crystalline Solid. 

Property of Crystalline Solid

• High melting point or long-range order ( due to  force of attraction) 

• They give clean cleavage ( means fix shape and volume) with a knife

• True solid ( means they have all the properties of solid) 

• High heat or enthalpy of fusion ( It is the amount of heat required to convert 1 mole of solid into a liquid known as the heat of fusion) 

• Melting point is directly proportional to the heat of fusion

• Anisotropic in nature ( Anisotropic means the different directions of crystalline solid have different physical properties value like Density, Conduct, shape, etc. ) 

• Example:- Diamond, Graphite, NaCl, KCl, CaSo4, CaCo3, etc.

Advantages Of Crystalline Solid|Key Points Of Crystalline Solid

• The arrangement of constituent(one of the parts that form something) particles(atoms, molecules, or ions)in a crystal is ordered and repetitive in 3D(Dimension).

• If we observe the pattern in one region (or area) of the Crystal, then we can predict accurately the position of particles in any other region (or area) of the Crystal that may be far from the place of observation. 

• Thus, the Crystal has a long-range order which means that there is a regular (having the same amount of space or part)pattern of arrangement of particles that repeats itself periodically(from time to time)over the entire crystal. 

Sodium chloride and Quartz are typical examples of crystalline solids. 

Amorphous Solid | Non-Crystalline Solid

The Term Amorphous comes from the Greek word amorphous, meaning no form.

 The arrangement of the constituent particles(atoms, molecules, or ions) in such a solid has only short-range order. 

In such an arrangement, regular and periodically repeating patterns are observed over a short distance only known as Amorphous solid or Non-Crystalline Solid. A regular pattern as scattered(spread out) is called an irregular pattern and the arrangement between irregular patterns is defined as disordered. 

Or 

They have irregular arrangements of particles of solid known as Amorphous Solid Or Non-Crystalline Solid. 

Property of Amorphous Solid

• They melt over a range of temperature or short-range order ( means melting starts after a certain temperature like plastic ( not a normal plastic) melt starting at 1200 degrees and before this temperature plastic doesn't melt this will happen due to low force of attraction between particles). 

• They have a low heat of fusion

• They are Pseudosolid Or super cooled liquid (  It is the type of solid in which they are solid and also liquid by the change in temperature known as Pseudosolid Or super cooled liquid). 

• They give irregular cleavage ( Irregular shape) with a knife. 

• Isotropic in nature ( Isotropic means they have the same value of physical properties in all the directions of amorphous solid like not conduct electricity in plastic). 

• Example:- Glass, Plastic, Rubber, Pitch, etc. 

Quartz

   

Quartz glass

The structures of quartz and quartz glass are crystalline solid and amorphous solid respectively. 

While the two structures are almost identical or shaped in the case of amorphous Quartz glass there is no long-range order.

The structure of an amorphous solid is similar to that of a liquid. Due to the difference in the arrangement or pattern of the constituent particles, then the two types of solid differ in their properties(arrangement or pattern of solid). 

Glass, rubber, and many plastics do not form crystals when their liquid solidify on cooling. These are called amorphous solid

Browse more Topics under Solid State

• General Characteristics Of Solid State 

• Classification Of Crystalline Solids

Advantages Of Amorphous Solid And Crystalline Solid 

•  Crystalline Solids have a sharp melting point. At a specific characteristic temperature, they melt abruptly (suddenly)and become liquid. 

• On the other hand, amorphous solids soften, melt and start flowing (become liquid or melt)over a range of temperature and can be moulded (to make a soft substance that has a particular shape)and blown (convert)into various shapes. 

• Amorphous solids have the same structural features as liquids and are conveniently regarded(known) as extremely viscous liquids. They may become crystalline at some temperature. Some glass objects from an ancient civilization are found to become milky in appearance because of some crystallization (formation of Crystal).

• Like liquids, amorphous solids tend to flow, though very slowly. Therefore, sometimes these are called pseudo solids or super cooled liquids. 

• Amorphous solids are isotropic in nature. Isotropic in nature means their properties such as mechanical strength, refractive index, electrical conductivity, etc., are the same value in all the directions where we move in amorphous solids. It is because there is no long-range order in them and the arrangement of the particle is not defined in all directions. Hence, the overall arrangement becomes equivalent in all directions. Therefore, the value of any physical property would be the same in any direction. 

• Crystalline solids are anisotropic in nature. Anisotropic in nature means that some of their physical properties like electrical resistance or refractive index show different values when we measured along the different directions in the same crystal. This arises or caused due to the different arrangement of the particles in different directions. 

Anisotropy in a crystal is due to different arrangements of particles along different directions

• This figure shows a simple two-dimensional pattern of arrangement of two kinds of atoms (the first atom is shown by a (large) blank circle and the second atom is shown by a (small) filled circle). Mechanical properties such as resistance to shearing stress might be quite difference in the two directions indicated in the figure (because Crystalline solids have regular arrangement due to this when moving in a different direction of Crystal then we get different values in different directions). Deformation in the CD direction displaces row which has two different types of atoms (displaces different C and D atoms) while in AB direction row made of one type of atoms are displaced (A displace A atom and B atom displace B atom). 

Difference between Crystalline solid and Amorphous solid

Property	Crystalline Solid	Amorphous Solid
Shape	Define characteristics of geometrical shape	Irregular shape
Melting point	Melt at a sharp and characteristics temperature	Gradually (slowly) soften over a range of temperature
Cleavage property	When cut with a sharp-edged tool, they split into two pieces and the newly generated surface is plain and smooth	When cut with a sharp-edged tool, they cut into two pieces with irregular surfaces
Heat of fusion	They have definite characteristics enthalpy of fusion	They do not have a definite enthalpy of fusion
Anisotropy	Anisotropic in nature	Isotropic in nature
Nature	True Solids	Pseudo solids or super cooled liquids
Order in an arrangement of Constituent particles	Long range order	Only short-range order.

Polycrystal Line Solid

Besides Crystalline and Amorphous solids, there are some solids that apparently appear amorphous solid but have microcrystalline(a small part of crystalline solid in amorphous solid)structures. These are called Polycrystal Line solids. 

Metal often occurs in polycrystalline conditions. Individual crystals are randomly oriented so a metal sample may appear to be isotropic nature even though a single crystal is an anisotropic nature. 

Amorphous solids are useful materials like glass, rubber, and plastics that find many applications in our daily lives. 

Amorphous silicon is one of the best photovoltaic materials available for the conversion of sunlight into electricity. 

Faq Of Amorphous Solid And Crystalline Solid

Question

Give 10 + examples of amorphous solid and crystalline solid. 

Answer

The examples of amorphous solids are,

• Plastic
• Glass
• Rubber
• Metallic glass
• Polymers
• Gel
• Fused silica
• Pitch tar
• Thin-film lubricants
• Wax
• Polyurethane
•  Teflon
• PVC(polyvinyl chloride)
• Cellophane
• Chalk
•  Quartz glass
•  Fiberglass

Examples of crystalline solids are,

• Quartz Calcite
• Sugar
• Mica
• Diamond
• Snowflakes
• Rock,
• Calcium fluoride
• Silicon dioxide
• Alum
• Sodium chloride(Nacl)
• Potassium Sulphate(K2SO4)
• Potassium nitrate(KNO3)
• Naphthalene
• Benzoic acid
• Copper
• Silver
• Iron
• Ice

Question

Is glass a Crystalline solid or non Crystalline? 

Answer

Glass is not a Crystalline solid but glass is a non-crystalline or an amorphous solid because glass has an irregular arrangement between glass particles

Question

Classify the following as amorphous or crystalline solids:
Polyurethane, naphthalene, benzoic acid, teflon, potassium nitrate, cellophane, polyvinyl
chloride, fibre glass, copper.

Answer:

Amorphous solids
Polyurethane, teflon, cellophane, polyvinyl chloride, fibre glass

Crystalline solids
Naphthalene, benzoic acid, potassium nitrate, copper

Question

Why is glass considered a super cooled liquid?

Answer:

Similar to liquids, glass has a tendency to flow, though very slowly. 

Therefore, glass is
considered a super cooled liquid. 

This is the reason that glass windows and doors are
slightly thicker at the bottom than at the top.

Question

The Refractive index of a solid is observed to have the same value along all directions.
Comment on the nature of this solid. Would it show cleavage property?

Answer: 

An isotropic solid has the same value of physical properties when we measured it in
different directions.

Therefore, the given solid, having the same value of the refractive index in all directions, is isotropic in nature. 

Hence, the solid is an amorphous solid.

When an amorphous solid is cut with a sharp-edged tool, it cuts into two pieces with
irregular surfaces.

Question

Which of the property of crystalline solid is not? 

• Anisotropic 

• Hard 

• Dense

• Isotropic

Answer

The property of a crystalline solid is not isotropic in nature. 

Question

What are Crystalline solids give 2 examples? 

Answer

Solid particles have a regular arrangement or pattern or define the geometrical shape known as Crystalline Solid. 

Examples: Quartz, calcite, sugar, mica, Diamond, etc. 

Question

What are the non Crystalline solid or Amorphous solid?  

Answer

Solid particles have an irregular arrangement or pattern or do not define the shape as known as Amorphous Solid. 

Question

What is the order of a Crystalline Solid? 

Answer

Particles are arranged in regular order with repeated patterns. They have a regular arrangement and ordered arrangement resulting in a definite geometric shape of solid particles. 

Question

A crystalline solid changes abruptly (suddenly)? 

Answer

Crystalline Solids have a sharp melting point. At a specific characteristic temperature in they melt abruptly (suddenly)and become liquid from solid(solid into liquid)when heated. 

Question

How many coordination no. of Crystalline Solid? 

Answer

Crystalline solids have six(6) coordination numbers. 

Browse more Topics under Solid State

• General Characteristics Of Solid State 

• Classification Of Crystalline Solids

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